In Japanese Patent No. 3557776, when a vehicle travels on a new road which is not present in a road map data stored in a storage medium, a navigation apparatus (e.g., a car navigation apparatus mounted to the vehicle) recognizes the new road based on a travel trace of the vehicle and sends information on the recognized new road to an information center. The information center updates a road map data based on the received new road information. That is, the information center has a new road learning function. However, the new road learning function described in Japanese Patent No. 3557776 cannot detect a road that is actually abandoned.
According to the new road learning function of Japanese Patent No. 3557776, the new road can be added. However, when a road is abandoned because of, for example, a new road construction, the abandoned road remains, and as a result, a route guidance using the abandoned road may be performed.
Additionally, in Japanese Patent No. 3557776, when the road map data is updated, all the updated road map data is transmitted to the navigation apparatus. That is, an excessively-large amount of data is transmitted to the navigation apparatus. This is also the case of a road instruction data. That is, all the road guidance data (road map data, road instruction data), which is an excessively-large amount of data, is transmitted.